There are numerous devices available which are capable of measuring gas pressure, such as an air compressor pressure gauge or a combined air valve and gauge typically found at automotive/service stations. These devices are capable of visibly indicating gas pressure to an operator. An air compressor gauge typically is mounted on an air tank away from the outlet of the compressed air supply line. For industrial painting installations, a building will typically have a compressed air distribution system. The system may include a wall mounted pressure gauge and a pressure regulator at each painting location. During painting, the pressure gauge may not be visible to the operator. Prior art in line pressure gauges have been too bulky and heavy to place in the air hose adjacent to the spray gun where it is readily visible to the operator.
Vehicle service stations typically use compressed air hoses for filling tires. Tires are filled with a valve and gauge assembly on the end of the hose which prevents air loss and indicates the air pressure in the tire. The valve and gauge assembly has the gauge mounted to one side of the air flow path through the supply line to the valve. Pressure gauges of this type require additional components which add to the complexity, bulk, and price of the device if one so desires to be able to measure the pressure of a fluid flowing through the line.